High-voltage circuit interrupter with a pair of fluid-conducting pivotally-mounted contact arms



Feb. 27, 1968 HIGH-VOLTAGE CIRCUIT INTERREJ W M. LEEDS PTER WITH A PAIR OF FLUID-CONDUCTING PIVOTALLY-MOUNTED CONTACT ARMS Filed Feb. 26, 1965 2 Sheets-Sheet 1 WITNESSES mfw INVENTOR Winthrop M. Leeds ATTORNEY Feb. 27, 1968 w. M. LEEDS 3,371,175 HIGH-VOLTAGE CIRCUIT INTERRUPTER WITH A PAIR OF FLUID-CONDUCTING PIVOTALLY-MOUNTED CONTACT ARMS Filed Feb. 26, 1965 2 Sheets-Sheet 2 l2 ii F I G. 2.

United States Patent 3,371,176 HIGH-VOLTAGE CIRCUIT INTERRUPTER WITH A PAIR OF FLUID-CONDUCTING PIVOTALLY- MOUNTED CONTACT ARMS Winthrop M. Leeds, Forest Hills, Pittsburgh, Pa., assignor to Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed Feb. 26, 1965, Ser. No. 435,560 10 Claims. (Cl. 280-448) ABSTRACT OF THE DISCLOSURE A high-voltage compressed-gas circuit interrupter has two pivotally-mounted fluid-conducting contact arms supported on a bearing portion of the high-pressure reservoir. Spaced pairs of stationary contacts, with resistance means connected therebetween, are electrically bridged by the contact arms in the closed-circuit position, and the arrangement is such that the two resistance sections are inserted electrically into the circuit during the opening operation. The arms may be rigidly connected together or may have a spring-biased lost-motion mechanical connection therebetween.

This invention relates, generally, to circuit interrupters and, more particularly, to circuit interrupters of the compressed-gas type suitable for extra high voltage (EHV) service.

Present live tank EHV, sulfur hexafluoride, (SP interrupters utilize two double-break rocker arm modules or units per phase for 345 kv., 3 modules per phase for 500 kv. and it is proposedto provide 4 modules per phase for 700 kv. breakers. An object of this invention is to increase the interrupting power per module, thereby reducing the number of modules required for a given rating with resulting economies in manufacture.

In a dual-pressure SP interrupter in which the contact members are in the low pressure region of the SP gas, the dielectric strength for a given gap separation can be approximately doubled by increasing the low pressure from 45 psig. (60 p.s.i. abs.) to 100 p.s.i.g. (115 psi abs). Furthermore, the circuit rate of rise of recovery voltage which could' be handled when interrupting a given short circuit current would be more than doubled by providing a two-step interrupting arrangement by which a shunting resistor is first inserted in the circuit and then the residual resistor current is cleared in a second interrupting gap.

Accordingly, another object of the invention is to provide the structural arrangement for achieving the foregoing improved results.

A further object of the invention is to utilize only one blast valve for controlling the flow of an interrupting gas to main and auxiliary interrupters having contacts which are opened in sequential relation.

Still another object of the invention is to provide for opening the main contacts first and the auxiliary contacts last and for closing the auxiliary contacts first and the main contacts last.

Other objects of the invention will be explained fully hereinafter or will be apparent to those skilled in the art.

In accordance with one embodiment of the invention, two hollow rocker contact arms are mounted side-by-side on bearings which surround the same blast valve. Sliding action of the valve first opens ports into the main contact arm which opens contact gaps at the two ends of the arm to insert parallel resistors across the pair of breaks. Further opening of the valve admits gas through ports into the second hollow contact arm. The contacts on the second or auxiliary arm are connected in series with the resistors'A lost-motion connection between the assigned to the Westinghouse Electric two arms delays the opening of the auxiliary contacts a predetermined amount behind the opening of the main contacts, thereby delaying the interruption of the residual resistor current. After the resistor current is interrupted, the mechanism releases the blast valve which is reclosed by spring action to shut off the gas flow.

For a better understanding of the nature and objects of the invention, reference may be had to the following detailed description, taken in conjunction with the accom panying drawings, in which:

FIGURE 1 is a view, partly in elevation and partly in section, of a portion of a circuit interrupter embodying principal features of the invention;

FIG. 2 is a diagrammatic view of the blast valve and portions of the contact arms of the interrupter shown in FIG. 1; and

FIG. 3 is a view, partly in elevation and partly in section, of a modification of the structure shown in FIG. 1.

Referring to the drawings, and particularly to FIG. l, the circuit interrupter shown therein may be generally of the type described in a c-opending application Serial No. 374,708, filed June 12, 1964, now US. Patent 3,291,- 947, issued December 13, 1966, to R. C. Van Sickle and Corporation. As shown in the drawing, the circuit interrupter comprises a low pressure metal tank or housing 11, a high pressure reservoir chamber 12, which may be mounted inside the housing 11, a pair of hollow rocker contact arms 13 and 14 rotatably mounted on a generally cylindrical bearing support 15, a generally cylindrical blast valve 16 slidably disposed inside the bearing support 15, a relatively stationary tubular main contact 17, a tubular auxiliary or resistor contact 18 spaced from the contact 17, and a terminal bushing 19 mounted on one end of the housing 11 and having a conductor 21 extending therethrough. Substantially only one-half of the interrupter structure is shown in FIG. 1 of the drawing. The other half of the structure is similar to that shown.

The terminal bushing 19 may be of a type suitable for extra high voltage service. The bushing is attached to the housing 11 by means of a mounting ring 22. As shown, the inner end of the conductor 21 supports the main contact 17 which is attached to the end of the conductor. A hollow resistor 23 is mounted on the inner end 24 of the terminal bushing 19. The auxiliary contact 18 is attached to one terminal 25 of the resistor 23 and is supported by the resistor. The other terminal 26 of the resistor is attached to the inner end 24 of the bushing 19 which supports the resistor 23 and the contacts 17 and 18. The terminal 26 of the resistor is electrically connected to the contact 17 and the terminal 25 is electrically connected to the contact 18. Thus, the resistor is connected across the contacts 17 and 18.

As shown more clearly in FIG. 2, the contact arms 13 and 14 are mounted side-by-side on bearings 27 and 28, respectively, on the bearing support 15 which is attached to the chamber 12 around an opening 29 in the chamber by means of bolts (not shown) extending through a flange 30 on the bearing support 15. The blast valve '16 has a closed end 31 and an open end 32 communicating with the opening 29in the chamber 12. The end 31 has a generally conical portion 33 extending inwardly to deflect gas through openings or ports 34 and 35 in the side wall of the valve. The valve 16 has a stem 36 which extends through a guide portion 37 on the outer end 38 of the bearing support 15. A valve spring 39 surrounding the valve stem 36 between the end 38 of the hearing support and a washer 41 on the valve stem biases the valve to the closed position. A pin 42 retains the washer 41 on the valve stem 36.

The valve 16 may be opened by a cam 43 rotatably mounted on a pin 44. The cam 43 has teeth 45 thereon engaged by a pawl 46 carried by an arm 47 pivotally mounted on the pin 44. The arm 47 is actuated by a link 48 which, in turn, is actuated by a breaker operating mechanism (not shown) of a type well known in the art. The pawl 46 is biased into engagement with the teeth 45 by a spring 49 disposed between one end 52 of the pawl 46 and a projection 51 on the arm 47. When the link 48 is moved upwardly, as shown in FIG. 2, the cam 43 is rotated counterclockwise to open the valve 16. At the end of the opening movement, the end 52 of the pawl 46 engages a pin 53 to disengage the pawl from the teeth 45, thereby permitting a spring 54 to return the cam 43 to the position shown in the drawing. The valve spring 39 then recloses the valve 16. The arm 47 is returned to the position shown in the drawing when the breaker is reclosed.

As shown in FIG. 1, the housing 11 may be supported and insulated from ground by a porcelain column 55, the upper end of which may be cemented to a mounting ring 56 which is attached to an annular member 57 by bolts 58. The member 57 may be welded to the housing 11 around an opening 59 in the bottom of the housing.

The housing 11 contains an interrupting gas, preferably sulfur hexafluoride (SP at a relatively low pressure,

for example, 100 p.s.i.g. The high pressure chamber 12 contains the interrupting gas at a relatively high pressure, preferably at least 200 p.s.i.g. The high pressure gas is supplied to the chamber 12 through an insulating tube 61 which is disposed inside the column 55 and extends from a main high pressure reservoir (not shown). Low pressure gas may be drawn from the housing 11 through the column 55, compressed by a compressor (not shown) and returned to the high pressure reservoir which, as previously stated, is connected to the chamber 12 through the tube 61.

The contact arm '13 carries an arc extinguishing unit 62 at each end of the arm. Likewise, the contact arm 14 carries an arc extinguishing unit 63 at each end of the arm. The units 62 and 63 are similar in structure. They are generally of the type fully described in the aforesaid copending application. As shown, the unit 62 comprises an insulating orifice member 64 having an opening 65 therein for receiving the tubular stationary contact 17. A plurality of. contact fingers 66 are mounted on a tubular member 67 which extends inside the lower end of the tubular member 17 when the contacts are in the closed position. The contact fingers 66 are biased into engagement with the outside of the tubular member 17 by springs 68. As previously explained, the arc extinguishing units 63 are similar to the units 62.

As also previously explained, the circuit rate of rise of recovery voltage which can be handled by the interrupter may be increased by providing a two-step interrupting arrangement by which the shunting resistor 23 is first inserted in the circuit and then the residual resistor current is cleared in a second interrupter gap. In order to obtain the two-step operation, a lost-motion connection is provided between the contact arms 13 and 14. As shown, the lost-motion connection comprises a projection 71 on the contact arm 13 which engages a projection 72 on the contact arm 14 as the arm 13 is rotated counterclockwise by a link 73 pivotally attached to a projection 74 on the arm 13. The link 73 is actuated by the breaker operating mechanism. Thus, the auxiliary arm 14 opening action is delayed a predetermined amount behind the opening of the main arm 13. In this manner the interruption of the residual resistor current is delayed, for example, one-half cycle behind the opening of the main contacts which divert current into the resistor 23.

As explained hereinbefore, the blast valve 16 is opened during the interrupting operation. The slide action of the valve first opens ports 34 and 35 into the main contact arm 13 which opens contact gaps at the two ends of the arm to insert the parallel resistors across the pair of breaks. As the blast valve opens further, gas is admitted through ports into the auxiliary contact arm 14. The contacts on this second arm are connected in series with the resistors, thereby inselting the resistors into the circuit. After the resistor current is interrupted by the separation of the contacts carried by the auxiliary arm 14 from the stationary contacts 18, the mechanism releases the blast valve 16 in the manner hereinbefore described and the valve is reclosed by spring action to shut oil the gas flow.

It is desirable to provide biasing springs 75 which will maintain the two rocker arms at their full angular displacement with respect to each other while fully open or when being closed. This will assure that the resistor contacts which parted last on opening will engage first on closing so as to insert the resistors to damp out energizing transients. When the main contacts engage approxL mately one-half cycle later, the resistors are shorted out and the load current is then carried continuously through the main contacts. As shown more clearly in FIG. 2, each spring 75 is disposed between a projection 76 on the contact arm 14 and a similar projection (not shown) on the contact arm 13. Thus, the springs bias the contact arms toward their full angular displacement with respect to each other.

in order to conserve on the flow of high pressure gas through the main rocker arm after its resistor-inserting function has been accomplished, the rotation of the arm toward the open position can be arranged to cause at least partial blocking of the passageways through the arm by the movement relative to fixed cylindrical wall sections of the bearing support 15 surrounding the blast valve 16. As previously stated, the blast valve 16 is reclosed at the end of the opening operation, thereby completely stopping the flow of high pressure gas.

In the alternative arrangement shown in FIG. 3 the main contact arm 13 and the resistor contact arm 14 are fixed with respect to each other and rotate simultaneously, or they may be combined into one arm. The stationary contact 18 and the contacts of the arc extinguishing unit 63 have a long wipe to permit the contacts of the extinguishing unit 62 to open first and insert the resistor before the contacts of the unit 63' separate from the stationary contact 18 to interrupt the residual resistor current. In FIG. 3 the contacts are shown in the open position and the fiow of gas through the tubular contacts is indicated by the arrows. The flow of gas through the contacts in FIG. 1 is similar to that in FIG. 3.

As described in the aforesaid copending application, a double flow of the interrupting gas is obtained. That is, gas flows upwardly through the tubular contacts 17 and downwardly through the tubular contacts 67. The orifice member 64 directs the flow of gas through the tubular contacts.

The sequential operation of the contacts carried by the contact arms may be obtained by the lost-motion connection shown in FIG. 1 or by the long contact arrangement shown in FIG. 3. The one set of contacts opens first to divert current into the parallel resistor and the second set of contacts then opens to interrupt the residual resistor current. By providing the two-step interrupting arrangement the circuit rate of rise of recovery voltage is greatly increased. In this. manner the interrupting power of each interrupting unit or module of a circuit breaker can be increased, thereby reducing the number of modules required per phase for a given voltage. This results in economies in manufacture.

Since numerous changes may be made in the abovedescribed construction and difierent embodiments of the invention may be made without departing from the spirit and scope thereof, it is intended that all subject matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim as my invention:

1. A compressed-gas circuit interrupter comprising a metal housing containing interrupting gas at a relatively low pressure, a reservoir chamber containing interrupting gas at a relatively high pressure, spaced relatively stationary contacts disposed inside the housing, a bearing support attached to the chamber, a pair of hollow rocker contact arms each pivotally mounted adjacent the midportion thereof and rotatably mounted on the bearing support, said arms carrying contact means for sequentially engaging and disengaging the stationary contacts, and a single blast valve for controlling the flow of gas from the chamber through the hollow contact arms into the housing during opening movement of the contact arms.

2. A compressed-gas circuit interrupter comprising a etal housing containing interrupting gas at a relatively low pressure, a reservoir chamber containing interrupting gas at a relatively high pressure, spaced hollow relatively stationary contactsdisposed inside the housing, a bearing support disposed inside the housing, a pair of hollow rocker contact arms each pivotally mounted adjacent the mid-portion thereof and rotatably mounted on the bearing support, said arms carrying hollow contact means for sequentially engaging and disengaging the stationary con tacts, and a single blast valve opened to permit the flow of gas from the chamber through the contact arms and the contact means and the stationary contacts into the housing during opening movement of the contact arms.

3. A compressed-gas circuit interrupter comprising a metal housing containing interrupting gas at a relatively low pressure, a reservoir chamber containing interrupting gas at a relatively high pressure, spaced hollow relatively stationary contacts disposed inside the housing, a bearing support disposed inside the housing, a pair of hollow rocker contact arms each pivotally mounted adjacent the mid-portion thereof and rotatably mounted on the bearing support, said arms carrying hollow contact means for sequentially engaging and disengaging the stationary contacts, a single blast valve opened to permit the flow of gas from the chamber through the contact arms and the contact means and the stationary contacts into the housing during opening movement of the contact arms, and said valve being reclosed to stop the fiow of gas at the end of said opening movement.

4. In a compressed-gas circuit interrupter in combination, a metal housing containing interrupting gas at a relatively low pressure, a reservoir chamber containing interrupting gas at a relatively high pressure, spaced relatively stationary contacts disposed inside the housing, resistance means connected across said stationary contacts, a bearing support disposed inside the housing, a pair of hollow rocker contact arms each pivotally mounted adjacent the mid-portion thereof and rotatably mounted on the bearing support, contact means on each arm engaging one of the stationary contacts, means for rotating said arms in one direction to open the contacts in one sequence first to cause current to flow through the resistance means and then to open the circuit through the resistance means, said contacts being closed in the reverse sequence when the arms are rotated in the opposite direction first to establish a circuit through the resistance means and then to short out the resistance means, and a single blast valve opened to permit gas to fioW through the contact arms into the housing during opening movement of the contact arms.

5. In a compressed-gas circuit interrupter in combination, a metal housing containing interrupting gas at a relatively low pressure, a reservoir chamber containing interrupting gas at a relatively high pressure, spaced relatively stationary contacts disposed inside the housing, resistance means connected across said stationary contacts, a bearing support disposed inside the housing, a pair of hollow rocker contact arms each pivotally mounted adjacent the mid-portion thereof and rotatably mounted on the bearing support, contact means on each arm engaging one of the stationary contacts, means for rotating said arms in one direction to open the contacts in one sequence first to cause current to flow through the resistance means and then to open the circuit through the resistance means, said contacts being closed in the reverse sequence when the arms are rotated in the opposite direction first to establish a circuit through the resistance means and then to short out the resistance means, a single blast valve opened to permit gas to flow through the contact arms into the housing during opening movement of the contact arms, and said valve being reclosed the stop the flow of gas at the end of said opening movement.

6. In a compressed-gas circuit interrupter, in combination, a metal housing containing interrupting gas at a relatively low pressure, a reservoir chamber containing interrupting gas at a relatively high pressure, spaced relatively stationary contacts disposed inside the housing, resistance means connected across said stationary contacts, a generally cylindrical bearing support attached to said chamber, a pair of hollow rocker contact arms each pivotally mounted adjacent the mid-portion thereof and rotatably mounted on the bearing support, contact means on each arm engaging one of the stationary contacts, means for rotating said arms in one direction to open the contacts in one sequence first to cause current to flow through the resistance means and then to open the circuit through the resistance means, said contacts being closed in the reverse sequence when the arms are rotated in the opposite direction first to establish a circuit through the resistance means and then to short out the resistance means, a blast valve disposed inside the bearing support, and means for opening said valve to permit gas to flow through the contact arms into the housing during opening movement of the contact arms.

7. In a compressed-gas circuit interrupter, in combination, a metal housing containing interrupting gas at a relatively low pressure, a reservoir chamber containing interrupting gas at a relatively high pressure, spaced relatively stationary contacts disposed inside the housing, resistance means connected across said stationary contacts, a generally cylindrical bearing support attached to said chamber, a pair of hollow rocker contact arms each pivotally mounted adjacent the mid-portion thereof and rotatably mounted on the bearing support, contact means on each arm engaging one of the stationary contacts, means for rotating said arms in one direction to open the contacts in one sequence first to cause current to flow through the resistance means and then to open the circuit through the resistance means, said contacts being closed in the reverse sequence when the arms are rotated in the opposite direction first to establish a circuit through the resistance means and then to short out the resistance means, a blast valve disposed inside the bearing support, means for opening said valve to permit gas to flow through the contact arms into the housing during opening movement of the contact arms, and said valve being reclosed to stop the flow of gas at the end of said opening movement.

8. In a compressed-gas circuit interrupter, in combination, a metal housing containing interrupting gas at a relatively low pressure, a reservoir chamber containing interrupting gas at a relatively high pressure, spaced relatively stationary contacts disposed inside the housing, resistance means connected across said stationary contacts, a generally cylindrical bearing support attached to said chamber, a pair of hollow rocker contact arms each pivotally mounted adjacent the mid-portion thereof and rotatably mounted on the bearing support, contact means on each arm engaging one of the stationary contacts, means for rotating said arms in one direction to open the contacts in one sequence first to cause current to flow through the resistance means and then to open the circuit through the resistance means, lost-motion means on said arms providing the sequential opening of the contacts, said contacts being closed in the reverse sequence when the arms are rotated in the opposite direction first to establish a circuit through the resistance means and then to short out the resistance means, a blast valve disposed inside the bearing support, and means for opening said valveto permit, gas to flow through the contact arms into the housing during opening movement of the contact arms.

9. In a compressed-gas circuit interrupter, in combination, a metal housing containing interrupting gas at a relatively low pressure, a reservoir chamber containing interrupting gas at a relatively high pressure, spaced relatively stationary contacts disposed inside the housing, resistance means connected across said stationary contacts, a generally cylindrical bearing support attached to said chamher, a pair of hollow rocker contact arms each pivotally mounted adjacent the mid-portion thereof and rotatably mounted on the bearing support, contact means on each arm engaging one of the stationary contacts, means for rotating said arms in one direction to open the contacts in one sequence first to cause current to flow through the resistance means and then to open the circuit through the resistance means, lost-motion means on said arms providing the sequential opening of the contacts, said contacts being closed in the reverse sequence when the arms are rotated in the opposite direction first to establish a circuit through the resistance means and then to short out the resistance means, a blast valve disposed inside the bearing support, means for opening said valve to permit gas to flow through the contact arms into the housing during opening movement of the contact arms, and spring means biasing said arms in opposite directions to provide the sequential closing of the contacts.

10. Ina compressed-gas circuit interrupter, in combinas tion, a metal housing containing interrupting gas at a relatively low pressure, a reservoir chamber containing interrupting, gas at a relatively high pressure, spaced relatively stationary contacts disposed inside the housing, resistance means connected across said stationary contacts, a bearing support disposed inside the housing, hollow means including two fiuidconducting contact arms each pivotally mounted adjacent the mid-portion thereof and rotatably mounted in the bearing support, contact means on the hollow means engaging each one of the stationary contacts, means for rotating said hollow means in one direction to open the contacts in one sequence first to cause current to flow through the resistance means and then to open the circuit through the resistance means, said contacts being closed in the reverse sequence when the hollow means is rotated in the opposite direction first to establish a circuit through the resistance means and then to short out the resistance means, valve means disposed inside the bearing support and means for opening said valve means to permit gas to flow from the reservoir chamber through the hollow means into the housing.

References Cited UNITED STATES PATENTS 2,112,841 4/1938 Hill 200-150 3,291,947 12/1966 Van Sickle 200-148 FOREIGN PATENTS 649,547 9/ 1928 France.

ROBERT S. MACON, Primary Examiner. 

